Application claims priority under 35 U.S.C. xc2xa7119 of German Application No. 199 03 278.5 filed Jan. 28, 1999. Applicant also claims priority under 35 U.S.C. xc2xa7120 to PCT/DE99/04038 filed Dec. 15, 1999. The international application under PCT article 21(2) was not published in English.
The invention relates to a light box piston as defined in the introductory parts of claims 1 and 5.
Such a piston is known from JP-U 64-25446. The aim is to make such a piston, which per se already can be referred to as a light piston, even lighter.
Said problem is solved in connection with a piston of the type specified above by the characterizing features of the independent claims 1 and 5. Advantageous developments of the invention are the objects of the dependent claims.
Owing to the cavities located above the bolt hubs, such cavities being produced with the help of bent sleeves, weight is saved without impairing the strength of the hub support. The dissipation of heat for supporting the bolt is influenced at the same time. With a suitable arrangement of cooling oil nozzles, the dissipation of heat from the piston can be enhanced by providing the channel in the form of a passage opening through which the oil is flowing.
The inlet opening produced by the sleeve is in this connection located on the side next to the bolt hubs. Because of the narrower running surface on the counterpressure side, it is possible to arrange the bent sleeve in such a way that it extends approximately perpendicular to the axis of the hub bores (viewed from the top).
For producing the bent channel, it is necessary to later fit conventional casting machines, which permit only linear movements of the components of the cast-iron mold, with devices for swiveling the sleeves. Such devices are swiveling side trains arranged on a circular track, each supporting a bent core part having a tapering cross section.
The tapering is required in order to permit removal of the bent core part from the mold. An angle of about 6xc2x0 can be selected as the pull-up slant for the core part.
In a production by means of salt cores according to claim 5 instead of sleeves, the pull-up slant can be dispensed with because the salt core usually can be flushed and removed, as it is possible also with cooling channels, i.e. the salt core does not have to be pulled from the cast piston like a sleeve does.